I'd get two LED construction lights from screwfix, to keep the cost down (studio lights expensive!), and position them on each side of the box, and light the box up. The box is basically a soft white fabric, which will let light through, it will result in indirect light, softer and difused. . Once you have the lights, you can experiment with them, position them in various places, make notes, but don't change the position of the camera or the pen. Eventually, you will find out where to keep the lights the best.You mean have lights shining into it as well? I have the lights switched on in the inside so I am thinking maybe it is the Camera.
You are right the pictures really do not come out very well at all.